1. Field of the Invention
The present invention relates to a oneway clutch-apparatus which is assembled into an automatic transmission, or the like, of a car and relates to the technology for facilitating attachment, or the like, of a block bearing to a retainer.
2. Related Background Art
Generally, an automatic transmission of a car is provided with a planetary gear speed changing mechanism capable of three to five speeds, in addition to a torque converter serving as a fluid coupling, and performs speed change by properly fixing or releasing a constituent element (such as a sun gear or a planetary gear) of the planetary gear speed changing mechanism by the use of a frictional engagement means such as a clutch or a brake. As the frictional engagement means to be incorporated in the automatic transmission, a multiple disc wet type in which friction plates and separator plates are alternately provided is widely employed, except in some band brake types. A pressure oil from a transmission control hydraulic circuit is used for the pressure contact (frictional engagement) between the both plates. As these frictional engagement means, a member which incorporates a oneway clutch therein and achieves easier transmission control by freely rotating a gear shaft, or the like, in one direction of rotation is partially employed.
Recently, as a oneway clutch apparatus for automatic transmission, there is increasingly employed a roller-type clutch apparatus in which rollers are interposed as torque transmitting members between an inner race and an outer race and cam surfaces are formed on the inner race. The roller-type oneway clutch apparatus is provided with springs for biasing the rollers in a direction of engagement, block bearings for forming a predetermined space between the inner race and the outer race, and a retainer to be fitted on the inner race for retaining the springs and the block bearings.
The roller type oneway clutch apparatus has characteristics including that a dragging torque is low during racing, but has a problem that a constituent part thereof easily drops off during conveyance. That is, in .the roller-type oneway clutch apparatus, since the outer race which is a constituent part of the clutch apparatus is an output shaft or an input shaft of the automatic transmission, it naturally does not exist in a sub-assembly which is a part preceding to the assembling of the automatic transmission. As a result, it any impact is applied to this sub-assembly during conveyance, rollers, springs, or block bearings which are assembled in the inner race or in a retainer may fall off comparatively easily. In this case, since the product becoming defective is required to be processed separately, the working efficiency is deteriorated. Therefore, there is proposed, as disclosed, for example, in Japanese Patent Application Laid-Open No. 2002-349607 (on page 4, FIGS. 5 and 9), a roller type oneway clutch apparatus comprising various means for causing a retainer to latch and retain rollers, springs and block bearings.
The roller type oneway clutch apparatus disclosed in Patent Application Laid-Open No. 2002-349607 is excellent in terms of preventing its constituent part from falling off, but has a problem that an assembling work of a block bearing is slightly difficult. FIG. 9 is an enlarged view of the essential part of the roller type oneway clutch apparatus of the prior art, for showing a state that a block bearing is attached to a retainer. As shown in FIG. 9, there is formed on an inner race 5 a latching groove 15 in which a convex portion 51 formed on the lower surface of the block bearing 19 is fitted, and a block bearing pressing piece 81 is integrally formed on a columnar part 37 of the retainer 21 for pressing the block bearing 19 diagonally downward. In order to attach the block bearing 19 to the inner race 5 and the retainer 21, first the block bearing 19 is advanced toward the root of the columnar part 37 diagonally, as shown in FIG. 10, and then is depressed perpendicularly toward the outer peripheral surface of the inner race 5, thereby fitting the convex part 51 in the latching groove 15, while elastically deforming the block bearing pressing piece 81, as shown in FIG. 11.
As described above, in the roller type oneway clutch apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-349607, it is required to drive the block bearing 19 in two directions, that is, diagonally and perpendicularly, when it is attached to the inner race 5 and the retainer 21. For this reason, the process for driving the block bearing 19 with an automatic assembling machine becomes complicated and a high driving accuracy is required thereat, which resultantly causes line stop with high frequency due to defective assembling. Further, the time required for assembling each block bearing 19 becomes comparatively long, so that the productive efficiency is also deteriorated.